The Swiss all-time grand slam champion has not beaten Nadal in five slam encounters since his 2007 Wimbledon final triumph, in a period of dominance by the Spanish world number one.

But a combination of Federer's resurgence under Swedish mentor Stefan Edberg, and Nadal's blister-induced weakened serve, has thrown open the outcome of Friday's blockbuster semi-final.

Nadal was clearly discomfited by the ugly blister in the palm of his serving hand as he spluttered with seven double-faults, two on break points, in his battling four-set win over Grigor Dimitrov in the quarter-finals.

The 13-time grand slam champion, 27, complained that a lack of confidence in his weakened serve made him vulnerable against the rising Bulgarian star.

"I served slower. I served bad," said Nadal, who is on a 10-match winning run.

"I felt my biggest problem was the serve because serving like this gives me a problem with everything else," he added.

RAFAEL NADAL (Spain)

World ranking: 1

Birthdate: June 3, 1986

Height: 1.85m

Weight: 85kg

Plays: Left-handed

Turned pro: 2001

Career singles titles: 60

Grand slam singles titles: 13

Career prize money: $64,632,763

Best Australian Open result: Champion (2009)

"When you lose confidence with one important shot like the serve, then you are not able to play the rest of the shots with confidence.

"So I'm going to try to improve that, because I'll need it in the semi-final if I'm going to have the chance to be in the final."

With the defeat of three-time defending champion Novak Djokovic on the other side of the men's draw, and Federer's four-set defeat of triple runner-up Andy Murray, only the Swiss great now stands in the way of a third Australian Open final appearance for Nadal.

Former world number one Federer, now ranked sixth, is trying to prolong his fabulous career and show he is still capable of winning an 18th grand slam title, with his last coming at Wimbledon 2012.

The 32-year-old Swiss maestro last month hired six-time grand slam champion Stefan Edberg in an advisory coaching role, and said he is feeling good again about his tennis.

"It's an amazing result for me again to be in the semis. This one feels different because of the tougher times I've had in (last year's) slams, Wimbledon, at the US Open," Federer said.

"I am back physically. I'm explosive out there. I can get to balls. I'm not afraid to go for balls."

Federer said he will draw on Edberg's big-match experience to devise his strategy against Nadal, but clearly he is relishing the prospect of playing the Spaniard again on the big stage.

"He's been tough to play against, no doubt. I'm happy I get a chance to play him in a Slam again," said Federer, who lost to Nadal in the 2012 Australian Open semi-finals in their last Slam encounter.

Nadal is bidding to become only the third man to win each of the four grand slam titles twice should he get through to Sunday's final.

ROGER FEDERER (Switzerland)

World ranking: 6

Birthdate: August 8, 1981

Height: 1.85m

Weight: 85kg

Plays: Right-handed

Turned pro: 1998

Career singles titles: 77

Grand Slam singles titles: 17

Career prize money: $79,218,415

Best Australian Open result: Champion (2010, 2007, 2006, 2004)

Rafa holds impressive record

Despite his blister, Nadal will enter the semi-final as the favourite having racked up an impressive 22-10 career record against Federer.

The Spaniard has won the last four times the pair have met and Nadal also triumphed in their Melbourne Park semi-final two years ago.

"He's been tough to play against, no doubt. I'm happy I get a chance to play him in a slam again. I don't remember the last time we played," Federer said.

"The head-to-head record is in his favour. I'm looking forward to speaking to Stefan, because when we first spoke about my game, we spoke about playing Rafa as well.

"Stefan thought he had some good ideas, so I'm looking forward to what he has to say.

"Clearly with (coach) Severin Luthi, he knows him (Nadal) inside out. I'm looking forward to hear what the boys have to say. I hope I can get a win. We'll see."

Federer, who has been batting back retirement questions since 2009, said he was not going to be thinking too far ahead of his match against Nadal and felt that his age was tacitly lowering expectations upon him.

"Things don't get easier. But at the same time they might become more enjoyable (and)... maybe I can play with less pressure," he said.

"I still love competition. Still feel maybe there's something big around the corner.

"For me, it's (been) a dream run and I hope I can keep it up against Rafa."